The present invention relates to process equipment that handles/processes flowable/moveable materials that may be filled with a second solid phase, or which are just the flowable/moveable second solid phase. The action of such solids presents process wear surfaces with accelerated abrasion, corrosion, and/or erosion, to which the present invention provides improved resistance.
A variety of process equipment has wear surfaces that are subjected to accelerated abrasion, corrosion, and/or erosion including, for example, forming tools, extrusion and compounding equipment, size reduction and size classification equipment, orifices and related components, engines (turbine, diesel, and Otto cycle), projectile weapons (firearms), clipper blades and combs, and the like. Normally, such equipment handles liquid and gas process streams that contain a second, solid phase. Such solids impinge upon the process equipment wear surface and cause accelerated abrasion, corrosion, and/or erosion.
Additionally, some process equipment handles just the solids themselves, such as, for example, a web or thread of paper, fabric, plastic, or the like. Such solid web also presents process equipment wear surfaces with accelerated abrasion, corrosion, and/or erosion. Even air containing entrained particulates will accelerate the wear to pipe elbows, for example. Thus, it will be appreciated that process equipment represents a wide variety of equipment that have wear surfaces that are adversely affected by the relative movement between the wear surface and a solid in contact therewith, whether or not the solid is entrained in a gas or a liquid.
While affixing or applying a wear-hardening layer to the process equipment wear surfaces, such as, for example, a liner, or manufacturing wear surfaces from more rugged material addresses the accelerated abrasion, corrosion, and/or erosion to some extent, the artisan is readily aware that much more is needed for a variety of applications for a wide variety of process equipment.
Heretofore, a variety of hard surface coatings have been proposed. U.S. Pat. No. 5,891,523 proposes a pre-heat treatment of a metal combing roll prior to an electroless Ni coating with diamond and U.S. Pat. No. 4,358,923 propose electroless coatings of metal alloy and particulates that include polycrystalline diamond. Molding dies have been hard faced with electroless coatings of Ni—P and Ni—P—SiC (Handbook of Hardcoatings. Bunshah, R. F. Editor, Noyes Publishing, 2001). It also has been proposed to co-deposit other solid particles within electroless Ni—P coatings, including SiC, B4C, Al2O3, diamond, PTFE, MoS2, and graphite (Apachitei, et al., “Electroless Ni—P Composite Coatings: The Effect of Heat Treatment on the Microhardness of Substrate and Coating”, Scripts Materials, Vol. 38, No. 9, pp. 1347-1353, Elsevier Sciences, Ltd. 1958). Additional Ni—P wear coatings are discussed by Bozzini, et al., “Relationships among crystallographic structure, mechanical properties and tribiological behavior of electroless Ni—P (9%)/B4C films”, Wear, 225-229 (1999) 806-813; Wang, et al., “Scuffing and wear behavior of aluminum piston skirt coatings against aluminum cylinder bore”, Wear, 225-229 (1999) 1100-1108; Hamid, et al., “Development of electroless nickel-phosphorous composite deposits for wear resistance of 6061 aluminum alloy”, Material Letters, 57 (2002) 720-726; Palumbo, et al., “Electrodeposited Nanocrystalline Coatings for Hard-Facing Applications”, AESF SUR/FIN® Proceedings, 686, 2002 Proceedings; Mallory, et al., “Composite Electroless Plating”, Chapter 11, Electroless Plating: Fundamentals and Applications, American Electroplaters and Surface Finishers Society (1990); and Feldstein, et al., “Composite Electroless Nickel Coatings for the Gear Industry”, Gear Technology, The Journal of Gear Manufacturing, 1997. A general statement on the principal of electroless nickel plating is given in Wear in Plastics and Processing, Chapter 2. Metals and Wear Resistant Hardfacings; 171 (1990).